Spring



FIG. 1 is a top view of a spring showing my design;

FIG. 2 is a reduce scale left side elevation view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a reduce scale right side elevation view thereof;

FIG. 6 is a reduce scale left side elevation view thereof;

FIG. 7 is a rear elevation view thereof;

FIG. 8 is a front elevation view thereof; and,

FIG. 9 is a rear, left-side perspective view thereof.

The broken lines showing the teeth in FIGS. 1 and 2 are included for illustrating environmental structure and form no part of the claimed design. 

The ornamental design for a spring, as shown and described. 